So in our discussion of the blood pressure benefits of garlic a few days ago, the lead author of UAB’s study, Dr. David Kraus, stopped by and left a bit of a clarification in the comments. Since I doubt most people take the time to read the comments, I want to bring his clarification to the forefront.

Dr. Kraus’ first comment was:

David Kraus, senior author of the PNAS study Says:
October 27th, 2007 at 12:32 pm

The garlic used in the study was raw when crushed and then centrifuged to obtain the juice. Crushing allows the enzyme alliinase to convert alliin to allicin which being unstable rapidly decays to become the allyl sulfides, ajoene, and others. The majority of the products, about 80% according to other work, are diallyl disulfide and dially trisulfide both which are stable to cooking and release H2S when in contact with our cells.
Many of the previously documented healthful properties of garlic are now being shown to also be properties of H2S supplied by other routes, so it may turn out that the Black Box of our cells is really just churning out H2S.

I was pretty sure that I knew what he was saying, but I sent him an email to be sure. In it, I asked him if he was saying that it’s the diallyl sulfides that do most of the work of generating H2S and that, since they are heat-stable, cooking does not negatively affect this action.

Here is his response:

Scott, it is the organic polysulfides such as diallyl di or tri sulfides (both formed from the breakdown of unstable allicin) which are more heat stable than the parent compound allicin. It is the ingested polysulfides that are disassembled by metabolism with our cells to release H2S and it is H2S that signals the vascular muscle cells to relax, dilates the blood vessels, reduces the resistance to blood flow, and lowers blood pressure.

I hope this helps clarifies the process.
Dave

PS
There is much more to the H2S story. It is an antioxidant and can prevent significant damage of a heart attack, see our PNAS paper Elrod et al in Sept. A new paper due out in about a month will show that being exposed to H2S in a bath can extend life span by 70% in lab organisms - warm sulfur springs have been used for centuries as the “fountains of youth” - probably more fact than fiction.

So there you have it. You can cook your garlic and still benefit from its blood pressure lowering properties. Thanks to Dr. Kraus for taking the time to clarify.


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